How to fix iPhone 6 Plus Wi-Fi switch is gray

Trouble Phenomenon

IPhone 6 Wi-Fi cannot be used, the Wi-Fi address in “about iPhone” displays “unknown”.

Repair Process

After testing, we find there is not any icon in “settings”, as shown in picture 1-31.

Picture 1-31

After dissembling, we find the Wi-Fi chip has been replaced and there are enameled wires under solder pad. Therefore, the improper enameled wires and unqualified working condition may cause the trouble. Remove the Wi-Fi chip directly and measure the diode data of each pin on solder pad. Comparing with normal motherboard, the measured data is normal. After removing Wi-Fi, the measured diode data of PCIE bus is infinite. We can only measure whether the circuit is connected between PCIE bus (as shown in picture 1-32) and coupling circuit C0703, C0704, C0705, C0706, C0720, C0721 (as shown in picture 1-33).

Picture 1-32

Picture 1-33

We find the circuits between solder pad and coupling circuit C0704, C0705 are open circuits through measurement. After checking the PCB circuit diagram , we find the circuits between solder pad and C0704 and C0705 will pass PP3169_RF and PP3166_RF, as shown in picture 1-34 and 1-35.

Picture 1-34

Picture 1-35

Directly connect solder pad and test point with enameled wires, then paint UV Solder Resist , as shown in picture 1-36 and 1-37. Reassemble Wi-Fi chip and test after power on. The Wi-Fi address still displays “unknown”.
Picture 1-36

Picture 1-37

Next, remove Wi-Fi chip again and measure the diode data of all pins on solder pad. We find the previous repaired places still in breakage. It connects or disconnects sometimes. In PCB circuit diagram, find the resetting pull-down resistance R0719, as shown in picture 1-38.

Picture 1-38

Directly place enameled wire from resetting pull-down resistance, as shown in picture 1-39.

Picture 1-39

Finally, reassemble Wi-Fi chip and test after power on. “About iPhone” displays Wi-Fi address. The trouble is removed.

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